barcode

The Columbia Encyclopedia, 6th ed.

Copyright The Columbia University Press

barcode, computer coding system that uses a printed pattern of lines and bars to identify such things as products, mail and packages, and customer accounts; the term also is used for similar coding systems that do not use bar-based patterns. Barcodes are read by optically scanning the printed pattern and using a computer program to decode the pattern. In a linear barcode system, the code itself contains no information about the item to which it is assigned but represents a string of identifying numbers or letters. When the code is read by an optical scanner linked to a computerized or networked device, the device can provide and record information about the item, such as its price or the quantity sold, from and to databases.

Americans Bernard Silver and Norman Woodland the first barcode system in the 1940s. The first standardized barcode adopted for general use was the linear Universal Product Code (UPC), chosen by North American supermarkets in 1973; it entered commerical use in 1974, but barcode scanners were not widely deployed until the 1980s. The original UPC used a set of two dark (usually black) and two light (usually white) bars of specified thicknesses to represent 12 numbers, but beginning in 2005 the Uniform Code Council, now known as GS1 US, adopted the similar European Article Numbering Code (EAN), which encodes 13 numbers and had become the international standard. The standards for the international product barcode system are managed by GS1, formerly known as EAN International, which is based in Brussels. The dark bars may be from one to three units wide and the light bars from one to four units. For registration purposes two one-unit dark bars are placed at each end and in the middle. Each item is assigned a unique numeric code, which is printed as a barcode on the item's packaging.

So-called two-dimensional (2D) barcodes permit the encoding of information about an item in addition to an identifying code. In a 2D barcode, two axes, or directions, are used for recording and reading the codes and the bar size is reduced, increasing the space available for data in the way that a column of words improves on a column of letters. Some 2D codes do not use bars, such as the United Parcel Service's hexagon-based Maxicode. Manufacturers and others now use 2D Quick Response (QR) codes on products and other objects to provide information associated with those items directly to individuals who can read the barcodes using smartphones.

An emerging technology, radio-frequency identification (RFID), could supplant the barcode in most applications. The newer radio-based devices overcome many of the limitations inherent in the barcode's optical technology.

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bar code

bar code (orbarcode) A printed machine-readable code that consists of parallel bars of varied width and spacing. The application most commonly observed is the coding on food and other goods that is read at the checkout and translated into a line of print on the bill showing product and cost. The information is also used to update stock records and provide sales statistics.

In the US the code used for this purpose is the Universal Product Code (UPC) and in Europe it is the European Article Numbering (EAN) code. The UPC decodes initially into two five-digit numbers. The first five identify the supplier and the next five are the item number within that supplier's range of goods. From this information the checkout terminal can access the details to be printed on the bill. The EAN code has a two-digit number to indicate country of origin, then the two five-digit numbers, followed by a check digit. The EAN arrangement simplifies the allocation of codes to suppliers. Only the two-digit code and the format need to be agreed internationally.

Other codes are used for shop-floor data collection, library systems, and monitoring the circulation of confidential documents. The advantage of bar codes is that they can be produced and read by relatively simple equipment. Codes used for these purposes are Code 39, Codabar, and “2 of 5”. See also bar code scanner.

Two-dimensional (2D) bar codes, e.g. PDF417, are becoming more common but do require a special reader. PDF-417 is a two-dimensional bar code that can store up to about 1800 printable ASCII characters or 1100 binary characters per symbol. The symbol is rectangular; the dimensions can be adjusted to grow with the data. There is no theoretical limit on the amount of data that can be stored in a group of PDF-417 symbols.

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bar code

bar code (Universal Product Code) Coded information consisting of thick and thin lines, and designed for computer recognition. At checkouts, a laser beam scans the bar code and a light-sensitive detector picks up the reflected signal, which consists of a pattern of pulses. The store's computer translates this into product information.

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